Botany MCQs for NEET — Practice Questions with Answers

Genetic information is transferred from the nucleus to the cytoplasm through RNA. Specifically, messenger RNA (mRNA) carries the genetic code from DNA in the nucleus to the ribosomes in the cytoplasm, where proteins are synthesized.

Reverse transcription is the process by which information is transferred from RNA back to DNA. This process is carried out by the enzyme reverse transcriptase, which is commonly found in retroviruses like HIV.

The correct answer is o4: A, C, D, E. Here's why:
- Degeneracy of code is related to the third member of codon (A) because multiple codons can encode the same amino acid, often differing in the third nucleotide.
- In codons, the first two bases are more specific (C) because they play a crucial role in determining the amino acid.
- The third base is considered the wobble position (D) because it can tolerate some variation without changing the amino acid.
- The genetic code is universal (E) as it is nearly the same in all organisms.

The diameter of a DNA molecule is uniform due to specific base pairing between purine and pyrimidine (o3). Purines (adenine and guanine) are larger, and pyrimidines (cytosine and thymine) are smaller. This pairing ensures a consistent diameter because each base pair consists of one purine and one pyrimidine, maintaining the uniform width of the DNA double helix.

In DNA replication, the primer is a small ribonucleotide polymer (o2). Primers are short RNA sequences that provide a starting point for DNA synthesis. They are synthesized by the enzyme primase and are necessary for DNA polymerases to begin adding DNA nucleotides.

Nonsense codons, also known as stop codons, are sequences in the genetic code that do not code for an amino acid and signal the termination of protein synthesis. When the ribosome encounters one of these codons (UAA, UAG, or UGA), it terminates translation, releasing the newly synthesized polypeptide chain. This is crucial for ensuring proteins are made to the correct length and function properly.

DNA Polymerase I has a 3' to 5' exonuclease activity that allows it to proofread and correct errors in DNA replication. When a wrong base is inserted, the enzyme can remove the incorrect nucleotide and replace it with the correct one, ensuring high fidelity during DNA replication.

Ribonuclease P and Peptidyl transferase are both ribozymes, which are RNA molecules with enzymatic activity. Ribonuclease P is involved in tRNA processing, while Peptidyl transferase is a component of the ribosome responsible for forming peptide bonds during protein synthesis.

Translation is the process by which the genetic code carried by mRNA is decoded to produce the specific sequence of amino acids in a polypeptide chain. The steps involved in translation are Initiation, Elongation, and Termination. Replication is the process of copying DNA, not a step of translation.

Aminoacyl-tRNA synthetase is an enzyme that attaches the appropriate amino acid onto its tRNA. This process is known as 'charging' or 'aminoacylation' of the tRNA. Therefore, the enzyme facilitates the adoption of amino acids by a tRNA molecule.